1. Field of the Disclosure
This disclosure relates generally to apparatus and methods for completing a wellbore for the production of hydrocarbons from subsurface formations, including fracturing selected formation zones in a wellbore, sand packing and flooding a formation with a fluid.
2. Background of the Art
Wellbores are drilled in subsurface formations for the production of hydrocarbons (oil and gas). Modern wells can extend to great well depths, often more than 1500 meters. Hydrocarbons are trapped in various traps in the subsurface formations at different depths. Such sections of the formation are referred to as reservoirs or hydrocarbon-bearing formations or zones. Some formations have high mobility, which is a measure of the ease of the hydrocarbons flow from the reservoir into a well drilled through the reservoir under natural downhole pressures. Some formations have low mobility and the hydrocarbons trapped therein are unable to move with ease from the reservoir into the well. Stimulation methods are typically employed to improve the mobility of the hydrocarbons through the reservoirs. One such method, referred to as fracturing (also referred to as “fracing” or “fracking”), is often utilized to create cracks in the reservoir to enable the fluid from the formation (formation fluid) to flow from the reservoir into the wellbore. To fracture multiple zones, an assembly containing an outer string with an inner string therein is run in or deployed in the wellbore. The outer string is conveyed in the wellbore with a tubing attached to its upper end and includes various devices corresponding to each zone to be fractured for supplying a fluid with proppant to each such zone. The outer string includes certain profiles where the inner string may be engaged to perform a wellbore operation. For selectively treating a zone in a multi-zone wellbore, it is desirable to have an inner string that can be selectively set corresponding to any zone in a multi-zone well and perform a well operation at such selected zone. Once a zone has been treated, the wellbore is filled with the treatment fluid, which may include a base fluid, such as water, proppant, such as sand or synthetic sand-like particles and an additive, such as guar. A locating tool in the inner string is often used to engage with a profile in the outer string to provide a flow path from the outer string to the inner string to remove treatment fluid from the wellbore.
The disclosure herein provides apparatus and methods for engaging the inner string with the outer string at selected profiles in the outer string.